This invention pertains to electric lamp sockets and, more particularly, is concerned with lamp sockets having stripless wiring terminals.
Portable lighting units, which include desk lamps, floor lamps, and the like, use a lamp socket assembly usually enclosed in either a paper sleeve or a metal shell. The socket assembly is also called a "lampholder" or an "interior".
During manufacture of the lighting unit an electric cord set must be electrically connected to the socket assembly. In the past this has usually been accomplished by use of screw terminals.
Underwriter's Laboratories (UL) Standards applicable for portable lamp screw terminals call for the end of stripped wires to be either tin dipped or otherwise restrained to prevent unraveling of the wire strands. Alternately, the wires may be soldered to the terminals. Either method requires semi-skilled labor and takes longer than desired, thereby increasing the cost of the assembled lamp. This problem has long been recognized as evidenced by a number of patents directed to electric lamp sockets having stripless terminals. Stripless terminals may be broadly grouped as being of the insulation piercing type of the insulation displacing type.
Examples of patents dealing with the insulation piercing type are U.S. Pat. Nos. 2,728,059; 3,397,379; and 3,151,926. U.S. Pat. No. 2,728,059 issued to Lagin discloses an electric lamp socket with two insulation piecing terminals extending from a socket body. A separate snap-on cover covers the terminals. One of the terminals is connected to the screwshell while the other is connected to a switch contact within the body. The terminals are spaced so that the electric wires must be separated from each other. There is no provision to assure that the neutral wire is connected to the screwshell.
U.S. Pat. No. 3,397,379 issued to Puig calls for wires to be fed through separate passages in a threaded body to be proximate insulation piercing terminals. A separate sleeve with a mating thread is screwed onto the body and presses the wires against the terminals.
U.S. Pat. No. 3,151,926 issued to Schick et al. describes a lamp socket of the type intended to be placed in parallel along the length of an electric cord (e.g., Christmas lights). The socket body has a channel into which an electric cord is placed. Terminals within the channel pierce the cord's insulation. A separate wedge piece is clipped to the body to hold the cord in the channel and to provide strain relief.
The sockets described above are not one piece assemblies and, furthermore, do not appear adaptable for use in standard paper or metal shells.
The aforeincorporated U.S. Pat. No. 4,283,107 issued to the present applicant divulges a one-piece socket assembly having terminals of the insulation displacing type eliminating the need to strip insulation from the cord set.